The present invention relates to electroporation and pertains particularly to an apparatus with connective electrode template for electroporation therapy.
The present invention relates to the treatment of ailments in humans and other mammals, and more particularly, to an improved method and apparatus for the application of controlled electric fields for in vivo delivery of genes and pharmaceutical compounds into live cells of a patient by electroporation.
A cell has a natural resistance to the passage of molecules through its membranes into the cell cytoplasm. Scientists in the 1970's first discovered "electroporation", where electrical fields are used to create pores in cells without causing permanent damage to them. This discovery made possible the insertion of large molecules directly into cell cytoplasm. Electroporation was further developed to aid in the insertion of various molecules into cell cytoplasm by temporarily creating pores in the cells through which the molecules pass into the cell.
Electroporation has been used to implant materials into many different types of cells. Such cells, for example, include eggs, platelets, human cells, red blood cells, mammalian cells, plant protoplasts, plant pollen, liposomes, bacteria, fungi, yeast, and sperm. Furthermore, electroporation has been used to implant a variety of different materials, referred to herein as "implant materials", "implant molecules", "implant agents". These materials have included DNA, genes, and various chemical agents.
Electroporation has been used in both in vitro and in vivo procedures to introduce foreign material into living cells. With in vitro applications, a sample of live cells is first mixed with the implant agent and placed between electrodes such as parallel plates. Then, the electrodes apply an electrical field to the cell/implant mixture.
With in vivo applications of electroporation, electrodes are provided in various configurations such as, for example, a caliper that grips the epidermis overlying a region of cells to be treated. Alternatively, needle-shaped electrodes may be inserted into the patient, to access more deeply located cells. In either case, after the implant agent is injected into the treatment region, the electrodes apply an electrical field to the region. Examples of systems that perform in vivo electroporation include the Electro Cell Manipulator ECM 600 product, and the Electro Square Porator T820, both made by and available from the BTX Division of Genetronics, Inc.
Electroporation has been recently suggested as an alternate approach to the treatment of certain diseases such as cancer by introducing a chemotherapy drug directly into the cell. For example, in the treatment of certain types of cancer with chemotherapy it is necessary to use a high enough dose of a drug to kill the cancer cells without killing an unacceptable high number of normal cells. If the chemotherapy drug could be inserted directly inside the cancer cells, this objective could be achieved. Some of the best anti-cancer drugs, for example, bleomycin, normally cannot penetrate the membranes of certain cancer cells effectively. However, electroporation makes it possible to insert the bleomycin into the cells.
A number of experiments have been conducted to test therapeutic application of electroporation for cancer treatment in a process now termed electrochemotherapy. This treatment is carried out by infusing an anticancer drug directly into the tumor and applying an electric field to the tumor between a pair of electrodes. The field strength must be adjusted reasonably accurately so that electroporation of the cells of the tumor occurs without damage to any normal or healthy cells. This can normally be easily carried out with external tumors by applying the electrodes to opposite sides of the tumor so that the electric field is between the electrodes. The distance between the electrodes can then be measured and a suitable voltage according to the formula E=V/d can then be applied to the electrodes. It would be desirable to have an electrode apparatus having electrodes that can be inserted into or adjacent to tumors so that predetermined electric fields can be generated in the tumor tissue for electroporation of the cells of the tumor.
One type of in vivo electroporation application presently under active research under the direction of the applicant is electro-chemotherapy, which uses electroporation to deliver chemotherapeutic agents directly into tumor cells. This treatment is carried out by infusing an anticancer drug directly into the tumor and applying an electric field to the tumor between a pair of electrodes. The molecules of the drug are suspended in the interstitial fluid between and in and around the tumor cells. By electroporating the tumor cells, molecules of the drug adjacent to many of the cells are forced or drawn into the cell, subsequently killing the cancerous tumor cell.
Electroporation in this application is especially beneficial because electroporation can help minimize the amount of implant agent used, these chemicals frequently being harmful to normal cells. In particular, less of the implant agent can be introduced into the tumorous area because the electroporation will enable more of the implant agent to actually enter the cell. Electroporation is also beneficial for chemotherapy because some of the most promising anti-cancer drugs, such as Bleomycin, normally cannot penetrate the membranes of certain cancer cells effectively. However, recent experiments with electroporation demonstrated that it is possible to insert the Bleomycin directly into the cells.
Known electroporation techniques (both in vitro and in vivo) function by applying a brief high voltage pulse to electrodes positioned around the treatment region. The electric field generated between the electrodes causes the cell membranes to temporarily become porous, whereupon molecules of the implant agent enter the cells. In known electroporation applications, this electric field comprises a single square wave pulse on the order of 1000 V/cm, of about 100 .mu.s duration. Such a pulse may be generated, for example, in known applications of the Electro Square Porator T820, made by the BTX Division of Genetronics, Inc.
Although known methods of electroporation may be suitable for certain applications, the electric field may actually damage the electroporated cells in some cases. For example, an excessive electric field may damage the cells by creating permanent pores in the cell walls. In extreme cases, the electric field may completely destroy the cell.